by Ken Quandt, Regional Sales Manager
Many turf managers fail to realize just how important the beneficial soil microbes are for maintaining healthy turf. These beneficial microbes are the best friends that a superintendent can have, yet they are often starved out and killed with fertilizer and chemical programs that wreak havoc on them. This is unwittingly done through a process that I like to call “The Vicious Circle”. It happens something like this:
- The turf is fed exclusively with synthetic nitrogen sources that do not contain enough carbon to adequately feed the soil microbes. This results in slow starvation for the microbes.
- The starving microbes, desperate for a source of carbon, deplete the soil of organic matter, which is the only other source of carbon available to them.
- The soil structure slowly begins to deteriorate because the class of organisms that flocculate, or glue the soil particles together to create a granular, well-aerated soil, are no longer being adequately fed. The soil then begins to compact and resemble adobe bricks.
- The high salt content in many synthetic fertilizers and the compaction of the soil combine to cause the roots of the plants to decline.
- The lack of sufficient soil organic matter tends to reduce the buffering capacity of the soil, which allows the high salt content synthetic fertilizers to cause increased damage to plant roots.
- The water-soluble synthetic fertilizers tend to promote surge growth that tends to build up thatch layers.
- The lack of adequate populations of beneficial microbes keeps the thatch from decomposing rapidly enough, so the thatch levels continue to build, particularly with some of the vigorous new cultivars of turf that we now have available.
- The build up of thatch gives the pathogenic organisms a wonderful place to breed.
- The pathogens sometimes run wild due to a lack of competition from the beneficial microbes that have been starved out.
- The weakened plants with poor roots systems, growing in compacted soils, are easily preyed upon by pathogenic organisms.
- Usually, toxic chemicals are then applied in an attempt to control the fungi, nematodes or other pathogens that are creating problems for the turf. Unfortunately, these toxic chemicals kill off more of the beneficial organisms.
- Further depleting the beneficial organisms sometimes opens the door for more exotic diseases to attack the turf, so more chemicals are applied and the problem only gets worse.
- Expensive, controlled release synthetic fertilizers are applied in an attempt to reduce the problems, but the soil microbes are still being starved because of a lack of carbon.
- The result is weakened turf that easily succumbs to stress factors such as traffic and heat. In a year with lots of stressful weather, the superintendents’ jobs become Hell!